fix: Variable description for master_username requirements (#367)

Co-authored-by: Phillip Constantine <phillip.constantine@cognex.com>

README.md

@@ -335,7 +335,7 @@ No modules.
 | <a name="input_manage_master_user_password"></a> [manage\_master\_user\_password](#input\_manage\_master\_user\_password) | Set to true to allow RDS to manage the master user password in Secrets Manager. Cannot be set if `master_password` is provided | `bool` | `true` | no |
 | <a name="input_master_password"></a> [master\_password](#input\_master\_password) | Password for the master DB user. Note that this may show up in logs, and it will be stored in the state file. Required unless `manage_master_user_password` is set to `true` or unless `snapshot_identifier` or `replication_source_identifier` is provided or unless a `global_cluster_identifier` is provided when the cluster is the secondary cluster of a global database | `string` | `null` | no |
 | <a name="input_master_user_secret_kms_key_id"></a> [master\_user\_secret\_kms\_key\_id](#input\_master\_user\_secret\_kms\_key\_id) | The Amazon Web Services KMS key identifier is the key ARN, key ID, alias ARN, or alias name for the KMS key | `string` | `null` | no |
-| <a name="input_master_username"></a> [master\_username](#input\_master\_username) | Username for the master DB user. Required unless `manage_master_user_password` is set to `true` or unless `snapshot_identifier` or `replication_source_identifier` is provided or unless a `global_cluster_identifier` is provided when the cluster is the secondary cluster of a global database | `string` | `null` | no |
+| <a name="input_master_username"></a> [master\_username](#input\_master\_username) | Username for the master DB user. Required unless `snapshot_identifier` or `replication_source_identifier` is provided or unless a `global_cluster_identifier` is provided when the cluster is the secondary cluster of a global database | `string` | `null` | no |
 | <a name="input_monitoring_interval"></a> [monitoring\_interval](#input\_monitoring\_interval) | The interval, in seconds, between points when Enhanced Monitoring metrics are collected for instances. Set to `0` to disable. Default is `0` | `number` | `0` | no |
 | <a name="input_monitoring_role_arn"></a> [monitoring\_role\_arn](#input\_monitoring\_role\_arn) | IAM role used by RDS to send enhanced monitoring metrics to CloudWatch | `string` | `""` | no |
 | <a name="input_name"></a> [name](#input\_name) | Name used across resources created | `string` | `""` | no |

variables.tf

@@ -211,7 +211,7 @@ variable "master_password" {
 }
 
 variable "master_username" {
-  description = "Username for the master DB user. Required unless `manage_master_user_password` is set to `true` or unless `snapshot_identifier` or `replication_source_identifier` is provided or unless a `global_cluster_identifier` is provided when the cluster is the secondary cluster of a global database"
+  description = "Username for the master DB user. Required unless `snapshot_identifier` or `replication_source_identifier` is provided or unless a `global_cluster_identifier` is provided when the cluster is the secondary cluster of a global database"
   type        = string
   default     = null
 }